Southern California researchers fear a mild El Niño has warmed the Pacific Ocean enough to leave sea lions without food in the choppy churning waters.
Workers at the Pacific Marine Mammal Center in Laguna Beach said they are treating twice as many California sea lions as one year ago.
The waters may be just warm enough to push squid and sardines deeper into cool waters, leaving the sea lions malnourished.
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One sea lion washed ashore before sunset Monday, and a witness took a photo of the thin sea mammal. Rescuers rely on the public to snap the pictures and alert them when something seems wrong.
"Are their hip bones showing? Are their rib cages showing? Or is this a nice plump animal that is just resting? Is the animal sitting up?" said Kirsten Sedlick of the Pacific Marine Mammal Center. "Some of the animals that we're seeing are just necessarily ... may be just be resting because of the high surf. It has been pretty choppy out there and it's difficult for them to swim and maintain that."
And killer whales may be taking advantage of the at-risk sea lions, at least in one such instance captured on video from Capt. Dave Anderson's boat.
"If the sea lions are having trouble finding food, then they may be going to different areas and that might bring the killer whales into a different spot so it's possible," Anderson said.
Healthy sea lions nursed back to health at the Laguna Beach center should be released back to the ocean in the next few weeks.